Concentric tubing hydraulic power unit, particularly for down-hole safety valve actuation

ABSTRACT

Concentric tubing is supplied with fittings and seals to define an annulus about the inner tubing through which hydraulic fluid may be selectively pressurized to operate a down-hole tubing safety valve. This construction permits the unit to be rotated without fouling the control means for the valve, permits the unit to be raised and lowered through a stuffing box-type tubing hanger and to be used in single or multiple completions.

United States Patent [191 Phipps et a1.

[ CONCENTRIC TUBING HYDRAULIC POWER UNIT, PARTICULARLY FOR DOWN-HOLE SAFETY VALVE ACTUATION [75] lnventors: Willis M. Phipps, Pearland; Marvin L. Holbert, Jr.; John K. McGee, both of Houston, all of Tex.

[73] Assignee: Gray Tool Company, Houston, Tex.

[22] Filed: May 10, 1972 21 Appl. No.: 252,101

[52] US. Cl 166/89, 166/72,'28S/133 A, 285/137 A [51] Int. Cl. E2lb 17/00 [58] Field of Search..... 166/242, 89, 72, 166/73; 175/215; 285/133 A, 137 A {56] References Cited UNITED STATES PATENTS 1,862,260 Edmunds 175/215 X Dec. 25, 1973 1,547,461 7/1925 Steele 175/215 X 2,494,803 1/1950 Frost et a1 285/133 A 3,850,264 9/1958 Grable 175/215 UX 3,151,680 10/1964 Parkhurst et a1. 285/133 A X 3,489,438 1/1970 McClure 175/215 X 3,664,441 5/1972 Carey 285/133 A X Primary Examiner-David H. Brown Attorney-John W. Malley et a1.

[ 5 7] 1 ABSTRACT Concentric tubing is supplied with fittings and seals to define an annulus about the inner tubing through which hydraulic fluid may be selectively pressurized to operate a down-hole tubing safety valve. This construction permits the unitto be rotated without fouling the control means for the valve, permits the unit to be raised and lowered through a stufiing box-type tubing hanger and to be used in single or multiple completions. 1

4 Claims, 3 Drawing Figures BACKGROUND OF THE INVENTION In most oil producing areas, each tubing string through which subterranean fluids are produced under pressure from a petroleum well is required to include a down-hole safety valve placed e.g. 200300 feet below the surface. Typical of valves in current use are the Otis valve illustrated at page 3,883 of the 1970-71 edition of the Composite Catalog of Oil Field Equipment and Services, Gulf Publishing Company, Houston, Texas, U.S.A. Note that the Otis valve as illustrated in stalled includes a 54 inch control line which proceeds to the surface beside the tubing string. At intervals the exterior control line is clamped to the tubing string. The use of such a control line prevents rotation of the tubing string during installation, as rotation would result in fouling of the control line. This and other installation mishaps can result in kinking or bending of the control line so it will not serve its only purpose. This necessitates additional drilling rig costs for control line repair. Also disadvantageous is the fact the tubing string having such an external control line cannot be raised or lowered through a stuffing box-type tubing hanger. Another sub-surface safety valve installation including an external /4 inch control line is illustrated under the Page Oil Tools section of the same Composite Catalog on page 3,997.

SUMMARY OF THE INVENTION Concentric tubing is supplied with fittings and seals to define an annulus about the inner tubing through which hydraulic fluid may be selectively pressurized to operate a down-hole tubing safety valve. This construction permits the unit to be rotated without fouling the control means for the valve, permits the unit to be raised and lowered through a stuffing box-type tubing hanger and to be used in single or multiple completions.

The principles of the invention will be further hereinafter discussed with reference to the drawing wherein a preferred embodiment is shown. The specifics illustrated in the drawing are intended to exemplify, rather than limit, aspects of the invention as defined in the claims.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIGS. la, lb and 1c represent an upper, an intermediate, and a lower longitudinal sectional view of a tubing string incorporating a down-hole safety valve served by a concentric tubing hydraulic power unit provided in accordance with the principles of the present invention.

DETAILED DESCRIPTION OF THE PRESENT LY PREFERRED EMBODIMENT tion, the valve 12 may be taken to be the Otis valve described above. Of course, the tubing string, minus the concentric control line, conventionally continues below the valve 12 tothe zone being produced from. For additional perspective, note that the tubing string [0 at its upper end, terminates in a tubing hanger 14 whicb is conventionally equipped to be mounted in a tubing head, e.g. as illustrated under Gray Tool Company at pages 2,236, 2,237, 2,242 and 2,2452,247 of the same Composite Catalog.

To assemble one joint J of the unit depicted, a sub 20 is made up on one end of the tubing 22 via threading 24 until the shoulder 26 on the end of the tubing abuts the shoulder 28 interiorly of the base of the interiorly threaded box 30 of the sub 20. The opposite end of the sub 20 is provided with an external frusto-conical sealing surface 32 for establishing a stored-energy resilient seal (of the kind illustrated at one end of the sealing rings shown on pages 2,251 and 2,259 of the same Composite Catalog).

The outer tubing 34 is slipped over the other end of the inner tubing 22 until its one end 36 abuts the box end 38 of the sub 20.

Next, a sub 40 is made up on the other end of the tubing 22 via threading 42 until its one end 44 abuts the opposite end 46 of the outer tubing 34. Making up the threaded connection at 42 places tension in the tubing 22.

The opposite end of the sub 40 is provided with a box 48 having an internal frusto-conieally curved sealing surface 50 configured for providing a stored-energy seal as aforesaid (see e.g. U. S. Pat. Nos. 2,766,829, 2,766,998 and 2,766,999).

An internally threaded collar 52 is slipped over the outside of the sub 40 and threaded at 54 into the opposite end 46 of the outer tubing 34.

The safety valve 12 is shown including an internally threaded box 56 and an internally threaded opening 58 laterally beside the box for threadably receiving one end of an hydraulic control line 60.

The box 56 threadably receives the exteriorly threaded pin end 62 of a crossover sub 64. The box end 66 of the cross-over sub 64 is configured as if it were constituted by the sub 40, the upper two-thirds of collar 52, and the upper end region of the tubing 22 merged into an integral part. Accordingly, corresponding parts of the box end of the sub 64 and other elements of the joint .la formed there are given corresponding numerals to the intermediate joint first described, suffixed by La. 7

The joint Jb formed at the upper end of the concentric casing string with the tubing hanger 14 is, as illustrated, in effect, an inversion of Ja. Accordingly, corersponding parts of Jb are given corresponding numerals, suffixed by b.

The threaded joints may be sealed, and locked if need be, at 68, e.g. by applying epoxy sealant to the threading.

The existence and continuity of the'conduit for supplying hydraulic fluidunder pressure to the valve 12 to control the latter should now be noticed.

Within the box 48a, the sub 64 is provided, below its threading, with an upwardly, inwardly facing frustoconical shoulder 70. A complementary shoulder 72 formed on the exterior of the sub 20a is maintained spaced above the shoulder 70 by engagement of the frusto-conical sealing surfaces of the box 48a and sub 64 creating an annular space 74. An axially directed bore 76 is formed in the sub 64, proceeding downwardly from intersection with the space 74 until it emerges to the exterior of the sub 64 at 78. The exit region is internally threaded at 80 permitting connection thereto of the oppostie end of the short control line 60. The control line 60 is, for instance, about one foot long. Guaranteed a sufficiently long production run to justify it, the casing of the valve 12 may be modified so as to integrally include the sub 64 and the control line 60.

The annular space 74 continues up between the subs 20 and 64, between the tubings 22 and 34, between the sub 40 and collar 52, to the upper end of the string to a point within the tubing hanger where the annular space ends at the seals 84, 32b and communicates with a passageway 86 which exits from the upper surface of the enlarged support portion 88 of the tubing hanger at a threaded port 90. Another segment of control line (not depicted) may be secured to the port 90, following installation of the tubing string, and eg led from the wellhead through a side outlet thereof to a supply of pressurized hydraulic fluid and conventional means for increasing, maintaining and reducing the pressure on the hydraulic fluid to operate the valve 12.

Note that where parts axially abut one another so as to otherwise cause the annulus 74 to be discontinuous, one or the other of the abutting parts is provided with a plurality of angularly spaced notches or flutes 92 in the end thereof. Thus, such notches 92 are shown provided in the box ends of the subs 20, and in the lower end of the sub 40.

When the lengths of tubing 22, 34 are standard, offthe-shelf lengths of pipe, there may not be accurate concentricity between the CD. of the tubing 22 and the ID. of the tubing 34 after one joint has been made up. However, upon make up of the next-upper joint, slight lateral movement may take place where the elements abut at 94, 96 to improve coaxiality. As an example, the tubing 22 may be standard 2% inch O.D., 1.995 inch I.D. P.E. tubing, and the tubing 34 may be 2% inch O.D. 8 RND. E.U.E. tubing.

lt should be recognized that the designs of the tubing hanger and valve per se are only marginally related to the invention described herein so that they may be varied considerably without departing from the principles of the present invention.

It should now be apparent that the concentric tubing hydraulic power unit, particularly for down-hole safety valve actuation as described hereinabove possesses each of the attributes set forth in the specification under the heading Summary of the Invention hereinbefore. Because the concentric tubing hydraulic power unit, particularly for down-hole safety valve actuation of the invention can be modified to some extent without departing from the principles of the invention as they have been outlined and explained in this specification, the present invention should be understood as encompassing all such modifications as are within the spirit and scope of the following claims.

What is claimed is:

1. Petroleum well completion equipment including:

an inner string of tubing including a plurality of joints;

an outer string of tubing including a plurality of joints;

said joints of said inner string of tubing including upwardly facing shoulder means;

said joints of said outer string of tubing including downwardly facing shoulder means;

the inner string of tubing being generally coaxially received with the outer string of tubing and respective of said upwardly facing shoulder means engaging and supporting respective of said downwardly facing shoulder means;

a tubing hanger having a longitudinal throughbore and external shoulder means for supporting the tubing hanger in a wellhead;

means sealing and securing the upper end of one of the strings of tubing in the tubing hanger throughbore;

means sealing the upper end of the other of the strings of tubing in the tubing hanger throughbore;

means defining flutes through at least one of each two respective engaging shoulder means and the outer diameter of the inner string of tubing being sufficiently smaller than the inner diameter of the outer stringof tubing that, including said flutes, a substantially annular passageway is defined throughout the lengths of said inner and outer strings of tubing, terminating at the upper extent thereof in the tubing hanger;

conduit means extending between the exterior of the tubing hanger and the upper extent of the annular passageway for supplying pressurized fluid to the annular passageway; and

sub means having a throughbore provided with sealing and securement means for sealingly connecting the throughbore of the inner string of tubing with down-hole tubing safety bore valve and for closing the lower extent of the annular passageway, said sub means further including conduit means extending between the exterior of the sub means and the lower extent of the annular passageway for communicating the latter with a pressurized fluid valve operating port of the down-hole tubing safety valve. I

2. The petroleum well completion equipment of claim 1 wherein the conduit means in the tubing hanger communicate with the exterior thereof above said shoulder means.

3. The petroleum well completion equipment of claim 1 wherein the inner string of tubing is constituted by a plurality of lengths of pipe having frusto-conical sealing surface means at each end thereof engageable to provide prestressed seals between said adjacentlengths of pipe.

4. The petroleum well completion equipment of claim 3 wherein the outer string of tubing includes lengths of pipe and collars screwed together in alternation, there being sufficient axial shortening of the outer string of tubing upon screwing of the last-mentioned lengths of pipe and said collars to ensure prestressing of said prestressed seals.

I F l l 8 

1. Petroleum well completion equipment including: an inner string of tubing including a plurality of joints; an outer string of tubing including a plurality of joints; said joints of said inner string of tubing including upwardly facing shoulder means; said joints of said outer string of tubing including downwardly facing shoulder means; the inner string of tubing being generally coaxially received with the outer string of tubing and respective of said upwardly facing shoulder means engaging and supporting respective of said downwardly facing shoulder means; a tubing hanger having a longitudinal throughbore and external shoulder means for supporting the tubing hanger in a wellhead; means sealing and securing the upper end of one of the strings of tubing in the tubing hanger throughbore; means sealing the upper end of the other of the strings of tubing in the tubing hanger throughbore; means defining flutes through at least one of each two respective engaging shoulder means and the outer diameter of the inner string of tubing being sufficiently smaller than the inner diameter of the outer string of tubing thaT, including said flutes, a substantially annular passageway is defined throughout the lengths of said inner and outer strings of tubing, terminating at the upper extent thereof in the tubing hanger; conduit means extending between the exterior of the tubing hanger and the upper extent of the annular passageway for supplying pressurized fluid to the annular passageway; and sub means having a throughbore provided with sealing and securement means for sealingly connecting the throughbore of the inner string of tubing with down-hole tubing safety bore valve and for closing the lower extent of the annular passageway, said sub means further including conduit means extending between the exterior of the sub means and the lower extent of the annular passageway for communicating the latter with a pressurized fluid valve operating port of the down-hole tubing safety valve.
 2. The petroleum well completion equipment of claim 1 wherein the conduit means in the tubing hanger communicate with the exterior thereof above said shoulder means.
 3. The petroleum well completion equipment of claim 1 wherein the inner string of tubing is constituted by a plurality of lengths of pipe having frusto-conical sealing surface means at each end thereof engageable to provide prestressed seals between said adjacent lengths of pipe.
 4. The petroleum well completion equipment of claim 3 wherein the outer string of tubing includes lengths of pipe and collars screwed together in alternation, there being sufficient axial shortening of the outer string of tubing upon screwing of the last-mentioned lengths of pipe and said collars to ensure prestressing of said prestressed seals. 